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A CONTINUOUS PRESS ARRANGEMENT AND A METHOD FOR
MANUFACTURE OF BUILDING PANELS
FIELD OF THE INVENTION
Embodiments of the present invention relates to methods and
arrangements thereto for manufacturing laminate panels.
BACKGROUND OF THE INVENTION
It is known that building panels may be manufactured by means of
continuous or discontinuous press methods.
A discontinuous press typically operates in cycles wherein a product
may be arranged under a displaceable press table which subsequently apply
pressure to the product to thereby form a laminate.
Continuous press arrangements typically comprise a device having
upper and lower continuous press belts which form a product path there
between. The continuous press belts feed a product along the product path,
whereby the device is configured to apply a continuous pressure to the press
belts to thereby press the product to a laminate while the product is being
fed
along the product path.
Laminate panels in various forms are also known in the art. Laminate
panels may comprise building panels, such as floor coverings, wall panels,
ceiling panels or like.
A flooring may have a wooden surface. Building panels having a
wooden surface may be of several different types. Solid wood flooring is
formed of a solid piece of wood in form of a plank. Engineered wood flooring
is formed of a surface layer of wood glued to a core. The core may be a
lamella core or a wood¨based panel such as plywood, MDF or HDF. The
wooden surface layer may as an example have a thickness of 2-10 mm.
A wooden flooring may also be formed by gluing a wood veneer to a
core, for example, a wood¨based panel such as particleboard, MDF or HDF.
Wood veneer is a thin wood layer, for example having a thickness of 0.2-1
mm. A building panel with a separate surface layer glued to a core of for
example HDF or plywood is more moisture stable than solid wood floorings.
Compared to solid wood and engineered wood floorings, wood veneer
floorings can be produced to a lower cost since only a thin wood layer is
used. However, a wood veneer layer cannot be sanded as a solid wood or
engineered wood flooring can be.
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As an alternative to wood floorings, laminate floorings are also
available. Direct pressed laminated flooring usually comprises a core of a 6
12 mm fibre board, a 0.2 mm thick upper decorative surface layer of laminate
and a 0.1-0.2 mm thick lower balancing layer of laminate, plastic, paper or
like material.
A laminate surface conventionally comprises two paper sheets, a 0.1
mm thick printed decorative paper and a transparent 0.05-0.1 mm thick
overlay intended to protect the decorative paper from abrasion. The
transparent overlay, which is made of a¨cellulose fibres, comprises small
hard and transparent aluminium oxide particles, which gives the surface layer
a high wear resistance.
The printed decorative paper and the overlay are impregnated with
melamine resin and laminated to a wood fibre¨based core under heat and
pressure. The two papers have prior to pressing a total thickness of about 0.3
mm and they are after pressing compressed to about 0.2 mm.
A wood veneer may have a lower impact resistance than laminate
floorings and the production cost is high, compared to laminate floorings,
when high quality veneers are to be used.
Recently new "paper free" floor types have been developed with solid
surfaces comprising a substantially homogenous powder mix of fibres,
binders and wear resistant particles referred to as WFF (Wood Fibre Floor).
The mix is applied on a wood¨based panel such as MDF or HDF, and
subsequently applying heat and pressure to the mix to form a surface layer on
the panel. Such a flooring and process are described in WO 2009/065769.
WO 2009/065769 also discloses a thin surface layer such as wood
veneer layer, which is applied on a sub¨layer comprising, for example, cork or
wood fibres mixed with a binder. The sub¨layer is applied on wood fibre
based core.
US 2,831,794 discloses a process for manufacturing veneer panels. A
green veneer is applied on a mat of resin coated core particles of ligno¨
cellulose fibrous particles. Adhesive is applied on the veneer to bond the
veneer to the fibrous core, and to form a dense surface zone in the fibrous
core. The material of the core serves to fill knot holes or open flaws in the
veneer. When heat and pressure is applied, the result is the formation of a
panel, with the surface layer of the particles filling whatever flaws or holes
would otherwise the present in the veneer.
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US 2,419,614 discloses a coated wood product wherein a plywood is
coated by a covering or overlay material consisting of mixtures of sawdust
and synthetic resin. The veneer layer is coated by the covering or overlay
material such that the veneer is no longer visible. The covering forms the
uppermost layer of the product.
In the above description, the different types of product have been
described with reference to floorings. However, the same material and
problems applies for other types of building panels such as wall panels,
ceiling panels, and for furniture components.
It has been found that manufacture of building panels, in particular
building panels comprising wood veneer, is associated with a number of
problems. For example, the moisture content of the product may cause
blisters for instance when the pressure decreases. In a continuous press,
maintaining a sufficient applied pressure against the product may pose a
challenge.
As will become apparent herein, some problems faced in the prior art
may be exacerbated in continuous manufacture of building panels comprising
a sub¨layer comprising powder and/or a granulate and/or a wood veneer
layer.
As will become apparent herein, some problems faced in the prior art
may be exacerbated in continuous manufacture of building panels comprising
a wood veneer layer, typically arranged on the sub¨layer.
Embodiments of the present disclosure address a need to provide
methods facilitating improvements in the manufacture of building panels and
improvements in the quality of building panels.
Embodiments of the present disclosure address a need to provide
devices facilitating improvements in the manufacture of building panels and
improvements in the quality of building panels.
SUMMARY OF THE INVENTION
It is a general objective of the present disclosure to facilitate improved
quality of building panels.
It is a further object facilitate improved economy of building panels.
It is a still further object to facilitate mitigate or at least lessen the
problem of blisters in building panels.
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It is a further object to facilitate a more even pressure gradient in
continuous production of building panels.
It is also an object to facilitate a more even temperature gradient in
continuous production of building panels.
It is an object to facilitate improved sealing systems in a continuous
press arrangement.
It is an object to facilitate controlled deairing of a product intended to
be pressed, in particular a sub¨layer comprising a powder or granulate, such
as wetted and optionally dried powder.
The continuous press arrangement according to aspects of the
disclosure may adopt isochoric and/or isobaric principles in the operation
thereof.
An isobaric system or process is characterized by constant pressure.
For example, the pressure in the pressure zone facilitated by the pressure
cushion may for example be facilitated by means pressurized fluid, such as
pressurized air and/or pressurized oil. Thereby, an isobaric process may be
facilitated.
A process may for example comprise the process of subjecting the
product to heat and pressure while the product is fed through the continuous
press arrangement, such as through product path, whereby the product is
acted on by the pressure in the pressure zone, via the press belt. In another
example, a fluid pressure acts on the one or more pressure bars, which are
urged towards the press belt and the product path with a provided pressure,
whereby an isobaric process may be facilitated. The press bars may be set to
a fixed distance, thereby a portion of the product path and/or the product in
the product path may have a constant volume.
An isochoric system or process is characterized by constant volume.
For example, mechanical pressure may, via the press belt, be transferred from
the press table to the product by means of one or more pressure bars eac
provided at a respective fixed distance from the press belt. Thereby, an
isochoric process may be obtained.
The continuous press arrangement may adopt isochoric and/or
isobaric principles in its operation, as will be explained herein.
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Accordingly, embodiments of the present invention preferably seek to
mitigate, alleviate or eliminate one or more deficiencies, disadvantages or
issues in the art, such as the above¨identified, singly or in any combination
by in a first aspect providing a continuous press arrangement for manufacture
5 of building panels, such as floor or wall panels. The arrangement
comprising
an upper rotatable inlet drum connecting to an upper rotatable outlet drum via
an upper continuous press belt and a lower rotatable inlet drum connecting to
a lower rotatable outlet drum via a lower continuous press belt. The upper and
lower press belts configured to form a product path there between for feeding
a product in a feeding direction in response to rotation of one or more of
said
drums or displacement of said press belt(¨s); an upper and a lower press
table, each comprising at least one displaceable pressure cushion configured
to be displaced into sealing abutment with the press belt for facilitating a
pressure zone. The pressure zone preferably being in shape of a
pressurizable volume extending along at least a portion of the path. The inlet
drums are configured to form respective angles phi between the respective
press belts and the product path at a position being downstream the inlet
drums and upstream the pressure cushion or press table, in the feeding
direction.
The arrangement preferably comprises one or more pressure bars
disposed upstream and/or downstream the pressure cushion, in the feeding
direction FD. The one or more pressure bars are configured to apply a
pressure to the upper press belt and/or the lower press belt respectively in a
direction towards the product path.
A further object of embodiments of the invention is to provide a
method for continuous manufacture of building panels, such as floor panels
or wall panels.
A still further object of embodiments of the invention is to provide a
method for pre¨heating a product in continuous manufacture of building
panels.
Another object of embodiments of the invention is to provide a
method for pre¨compressing a product in continuous manufacture of building
panels.
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An object of embodiments of the invention is to provide a method for
controlling deairing of a product in continuous manufacture of building
panels.
At least some of these and other objects and advantages that will be
apparent from the description have been achieved in a second aspect by a
method of manufacture of building panels, such as floor or wall panels, by
means of a continuous press arrangement having an upper rotatable inlet
drum connected to an upper rotatable outlet drum via an upper continuous
press belt and a lower rotatable inlet drum connected with a lower rotatable
outlet drum via a lower continuous press belt. The upper and lower press
belts configured to form a product path there between for feeding a product
in a feeding direction in response to rotation of said drums; an upper and a
lower press table each comprising a displaceable pressure cushion
configured to facilitate a pressure zone extending along at least a portion of
said path. An angle is formed between the press belt and the product at a
position downstream a centre axis of the inlet drums in the feeding direction,
and upstream the pressure cushion, preferably upstream the press table. The
size of the angles may be adapted by adapting a distance between the
respective centre axis of the inlet drums, such as a vertical V distance.
In any aspects of the disclosure or combinations thereof, one or more
of the pressure bars may comprise at least one circular cross¨section, for
example the pressure bar may be provided in the shape of a cylinder, such as
a rotatable cylinder.
In any aspects of the disclosure or combinations thereof, one or more
of the pressure bars may comprise at least one rectangular cross¨section, for
example the pressure bar may be provided in the shape of a rectangular non¨
rotatable bar.
In any aspects of the disclosure or combinations thereof, one or more
of the pressure bars may comprise at least one rectangular cross¨section, at
least one circular cross¨section, or combinations thereof. For example one or
more pressure bar may be provided in the shape of a rectangular non¨
rotatable bar and one or more pressure bar in the shape of a cylinder.
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Alternatively or additionally, the press belt may be heated by induction
heating. Induction devices may be arranged along the press belt and
configured to heat the press belt.
Induction heating can be used as the only heat source, however also
in combination with heated drums, hot air or oil.
Advantages of induction heating may include that heating time of the
press belt may be reduced, the temperature of the press belt may be varied at
a higher rate, such as faster. Induction devices may be provided outside,
such as upstream or downstream, or inside the pressure cushion.
A baseline temperature of the press belt may be facilitated by hot air
and/or hot oil, such as in the drums, and induction heating of the press belt
may provide additional or complementing heat.
The continuous press arrangement may compress the product or
reduce the thickness of the product by at least 10%, preferably at least 15%
more preferably at least 20%.
In a preferred embodiment, the one or more pressure bars and the
one or more pressure cushion may aggregated compress the product or
reduce the thickness of the product by up to 20%, such as up to 15% or up to
10%.
In particular, the one or more pressure bars and the one or more
pressure cushion may successively reduce the thickness to an aggregated
reduction in thickness of the product by at least 10%, preferably at least 15%
more preferably at least 20%.
In a preferred embodiment, the one or more pressure bars and the
one or more pressure cushion may be configured to obtain an aggregated
compression of the product or reduction in the thickness of the product by up
to 1 mm, preferably 1.5 mm more preferably at least 2 mm.
In particular, the one or more pressure bars and the one or more
pressure cushion may successively reduce the thickness to obtain an
aggregated reduction in thickness of the product by at least 1 mm, preferably
up to 1.5 mm, more preferably at least 2 mm.
A single pressure bar may be configured to reduce the thickness of
the product by at least 10% and/or at least 1 mm.
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In any aspects of the disclosure or combinations thereof, the
continuous press arrangement may be a continuous press arrangement for
continuous pressing or manufacture of a product comprising at least one
veneer layer, such as wood veneer. The at least one veneer layer may be a
top surface layer and/or a back¨surface layer of the panel.
In any aspects of the disclosure or combinations thereof, the
continuous press arrangement may comprise one or more pressure cushions,
such as two, three, four or five pressure cushions. The pressure cushions
may each facilitate a pressure zone, as explained herein. The one or more
pressure zones may each be configured to provide different pressures, such
as successively increasing pressures.
The press belt will displace vertically due to thickness variations in the
product. The thickness of the product may vary in the longitudinal extend and
in the transverse extent. The thickness variations may be due to, not limited
to, a varying thickness of the core, uneven distribution of adhesive, such as
adhesive provided in powder form, such as by means of scattering, or the
veneer may comprise a varying thickness, such as due to holes or cracks in
the veneer.
A veneer may also typically comprise portions of wood having
different hardness, i.e. different susceptibility to compression, thereby some
.. portions of the veneer may more easily be compressed than other portions of
the veneer. For example, a hard portion of a veneer with is relatively less
susceptible to become compresses may cause the pressure cushion to
displace vertically.
The press belt may also be displace due to a gap between individual
products being fed through the product path, since the pressure from the
pressure bar or pressure cushion acting on the opposite side of the press belt
may cause the press belt to bend slightly into the gap.
A consequence of the vertical motion of the press belt caused by
product being fed between the press belts, translates into movement of the
pressure cushion, when the pressure cushion is in abutment with the press
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belt. Thus, the pressure cushion may pitch and/or roll in response to product
being fed through the product path.
Additionally, a veneer, such as a veneer arranged as a surface layer of
the product, may be positioned with at least one of its edges, horizontally
displaced inside, i.e. closer to a center of the core, in relation to the edge
of
the core, i.e. an edges of the veneer may not be aligned with the edges of the
core. Consequently, the thickness of the product may vary also due to one or
more edges of the veneer, such as short edges extending transverse the
feeding direction, not being aligned or flush with a corresponding edge, such
as edges extending transverse the feeding direction, of the core.
Thus, the product may have a varying thickness both in the
longitudinal direction and in the transverse direction.
When different portions of the pressure cushion displace or move as
explained above, the pressure cushion may pitch and/or roll. The greatest
vertical displacement of the pressure cushion may occur along the edges of
the pressure cushion, typically along the most upstream edge portions of the
pressure cushion, in particular the corner sections of the pressure cushion,
since these portions of the pressure cushion will move in response to the
incoming product, where the variations in thickness are typically greatest.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects, features and advantages of which
embodiments of the invention are capable of, will be apparent and elucidated
from the following description of embodiments of the present invention,
reference being made to the accompanying drawings, in which
FIG.1A shows a continuous press principle
FIG.2 shows an exemplary process for producing a product according
to an embodiment of the disclosure.
FIG.3 shows in a perspective¨view of a building panel according to an
embodiment of the disclosure.
FIG. 4. shows details of an embodiment of the disclosure.
FIG 5A¨D show schematic illustrations of a continuous press
arrangement according to embodiments of the disclosure.
FIG 6 shows a schematic illustration of a continuous press
arrangement according to an embodiment of the disclosure.
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FIGS 7 is a schematic illustration of a continuous press arrangement
according to an embodiment of the disclosure.
FIG. 8 is a schematic cross view of details of the embodiment of
FIG.7.
5 FIG. 9A shows details of the embodiment of FIG.7.
FIG. 9B is an alternative implementation form the embodiment of
FIG. 8A.
FIG 9C is another alternative implementation form the embodiment of
FIG. 8A.
10 FIG.10 shows a continuous press arrangement according an
embodiment of the present disclosure.
FIG.11 shows a continuous press arrangement comprising induction
heating according an embodiment of the present disclosure. FIG.12 shows a
continuous press arrangement comprising a rotatable pressure bar according
an embodiment of the present disclosure.
FIG. 13 shows a continuous press arrangement according to a further
embodiment of the disclosure.
FIG.14 is a schematic illustration of details of a seal system pressure
cushion according to an embodiment.
FIG.15 is schematic illustration of details of a seal system of a
pressure cushion according to an embodiment.
FIG.16A is a schematic illustration of details of a press table and
pressure cushion according to embodiments.
FIG.16B is a schematic illustration of details of a pressure cushion
according to embodiments.
FIG.17 is a schematic illustration of a continuous press employing
isobaric principles.
FIG.18 is a schematic illustration of a continuous press employing
isochoric principles.
DETAILED DESCRIPTION OF EMBODIMENTS
Specific embodiments of the invention will now be described with
reference to the accompanying drawings. This invention may, however, be
embodied in many different forms and should not be construed as limited to
the embodiments set forth herein; rather, these embodiments are provided so
that this disclosure will be thorough and complete, and will fully convey the
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scope of the invention to those skilled in the art. The terminology used in
the
detailed description of the embodiments illustrated in the accompanying
drawings is not intended to be limiting of the invention. In the drawings,
like
numbers refer to like elements.
Referring to FIG.1, the continuous press arrangement may comprise
an upper inlet drum 42 in driving connection with an upper outlet drum 44 via
an upper continuous press belt 40 and a lower inlet drum 43 in driving
connection with a lower outlet drum 45 via a lower continuous press belt 41.
The upper and lower press belts are configured to form a product path 6 there
between. The press belts are configured to convey a product 9 along the
product path 6 in a feeding direction FD. A pressure arrangement 50 may
comprise a press table 51 (see e.g FIG.5A-5D, FIG.7, FIG.10) comprising one
or more pressure cushion 55 configured to provide a pressure zone 70 which
may extend along at least a portion of the path in the feeding direction FD
between the press belts 40, 41, preferably at least half the length of the
press
table 51 in the feeding direction. The pressure zone 70 may be a three¨
dimensional space. The pressure zone(¨s) 70 may be formed between the
upper¨ and lower pressure cushions and the upper and lower press belts
respectively.
The pressure zone 70, 70' may be a pressurizable space. The
pressure zone 70, 70' may be delimited in horizontal directions, such as in
the
feeding direction FD and transverse the feeding direction FD, by the pressure
cushion 55, 55'. The pressure zone 70, 70' may be delimited in a first
vertical
direction by the press table 51. The pressure zone 70, 70' may be delimited in
a second vertical direction by the press belt 40, such as downwards in the
case of the upper part of the continuous press arrangement. The second
vertical V direction may be opposite the first vertical direction. This is
shown
for instance in FIGS 10-12.
Hence, a pressure zone 70, may be formed within the boundaries
pressure cushion 55.
The pressure cushion 55 may seal the pressure zone 70 against the
ambient pressure Pa.
Pressure cushion may preferably be displaceable in relation to the
press table, such as in a vertical direction.
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To facilitate displacement of the pressure cushion 55, the press table
51 may comprise a displacement groove 60 configured to at least partially
receive the pressure cushion 55. The displacement groove 60 may extend
continuously, such as in a loop, in the press table 51, as shown in FIGS 8 and
16A. The displacement groove 60 may comprise a substantially rectangular
shape in a horizontal H plane. The displacement groove 60 may comprise a
substantially rectangular cross¨section in a vertical V plane.
In one embodiment, illustrated in FIGS 9A-9B, the pressure cushion
55 may comprise a seal frame 56 and/or a friction seal element 57 attached
to the seal frame to displace therewith. The seal frame 56 may displace at
least partially in the press table 51.
The friction seal element 57 may comprise a plurality of individual
friction seal elements extending contiguously.
The friction seal element 57 may comprise a plurality of individual
friction seal elements extending contiguously and configured to extend
continuously along the displacement groove 60.
As derivable from FIG.10, the at least one pressure bar P1, P2 may be
provided in the press table 51 at a position(¨s) upstream the pressure
cushion 55 in the feeding direction FD, such as upstream the entire pressure
cushion 55, such as upstream the seal frame 56, such as upstream the entire
seal frame 56, such as upstream the friction seal member 57, such as
upstream the entire friction seal member 57.
As derivable from FIG.10, the at least one pressure bar P-1, P-2 may
be provided in the press table 51 at a position(¨s) downstream the pressure
cushion 55 in the feeding direction FD, such as downstream the entire
pressure cushion 55, such as downstream the seal frame 56, such as
downstream the entire seal frame 56, such as downstream the friction seal
member 57, such as downstream the entire friction seal member 57.
The upper press table may be adjustable in a vertical direction to
thereby be adapted to the product intended to be fed through the product
path 6. The upper and lower press tables 51 may be stationary during
operation of the press arrangement. The drums 42, 44, 43, 45 may be
stationary during operation. The upper press belt 40 forms an angle phi' with
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the plane of the product path 6 or a front surface of the product and
correspondingly, the lower press belt may form an angle phi' with a plane H
of the product path or the front surface 5 and/or back surface 6 of the
product 9 such that there is play between the inlet drums and the product.
Typically, a first position of contact 3' between the product and the press
belt
may be in close proximity of a most upstream edge of the press table, in
respect of the feeding direction. According to aspects of the disclosure, the
product may be pre¨heated by thermal radiation from the press belt prior it is
feed between the press tables. The According to aspects of the disclosure,
the product may be pre¨heated by means of abutment with the press belt
prior being fed between the press tables. According to aspects of the
disclosure, the pre¨heating of the product may be adjusted by adjusting the
distance between the upper inlet drum and the lower inlet drum, to thereby
adjust the angle phi. For example, referring to FIG.6, by reducing the
distance
between the upper¨ and lower inlet drums, the angle phi will be reduced,
whereby the upper and lower press belts are brought into closer proximity of
the product path and/or product. Also, the first position of contact 3' may be
moved upstream in the feeding direction FD. Thereby, increased pre¨heating
is achieved. Thereby, the continuous press may be made smaller and thus
more economic.
The product may comprise a binder which may be provided in the
shape of a powder. The powder typically comprises a fraction of air, which is
expelled on the sides of the product when pressure is applied by the pressure
cushion. The expelling of air may alter the properties of or distort the
powder
layer or displace a portion of the powder thereof and may thus have negative
effects for instance on the quality and/or the appearance of the product. For
example, should the powder layer e.g. comprise a printed pattern.
To summarize, heat is applied mainly by the heated press belt. The
press belt may be heated by heating the drums, however the press belt may
additionally or alternatively be heated by hot air or hot oil in the pressure
zone
and/or in the drums.
To summarize, a product is fed through the continuous press
arrangement having a play in relation to the inlet and outlet drums
respectively. Heat is conducted to the product from the press belt at least as
from a point of first contact between the press belt and the product. The
product may however in addition be pre¨heated by the press belt prior
contact therewith, as will be explained herein.
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Alternatively or additionally, the press belt may be heated by induction
heating. Induction devices may be arranged along the press belt and
configured to heat the press belt.
Induction heating can be used as the only heat source, however also
in combination with heated drums, hot air or oil. Thus, induction heating,
alone or in combination with any of the aspects of the disclosure.
A pressure is applied by the pressure cushion downstream the inlet
drums, and said pressure may be relieved as the product is fed past the
.. pressure cushion.
Thereby, the pressure applied to the product over the press
arrangement 80 may form a pressure curve, such as pressure as a function of
time or distance. As explained herein, embodiments of the aspects of the
present disclosure may facilitate that the pressure curve is rendered more
even or more isobaric, such as decreasing the rate of pressure change
upstream and/or downstream the pressure zone.
Thereby, the temperature of the product, such as the surface
temperature at the front surface 5 or back surface 6 or the core 10 or the
temperature of the binder, over the press arrangement 80 forms a temperature
curve, such as temperature as a function of time or distance. As explained
herein, embodiments of the aspects of the present disclosure may facilitate
that the temperature curve is rendered more even, such as decreasing the
rate of temperature change upstream and/or downstream the pressure zone.
FIG.2 illustrates an exemplary composition of layers of a product 9
intended to be pressed. The product may comprise one or more layers. In one
embodiment the product comprises a first layer 11 is typically provided to a
board 10, which may be a wood¨based board, such as HDF, MDF or like as
discussed above. The first layer in shape of a sub¨layer 11 may comprise a
powder, such as a dry powder or a granulate, such as wetted dried powder. It
should be appreciated that the term powder layer may in the following text
include the variant granulate layer. A second layer in shape of a surface
layer
12 may be provided to the product, interspacing the first layer between the
second layer and the board. The second layer may for example comprise a
printed pattern, paper, wood veneer or combinations thereof.
Now referring to FIG.3 showing an exemplary building panel
comprising the board 10, a sub¨ layer 11 in the shape of a powder layer, and
a surface layer 12 in the shape of a veneer.
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A schematic illustration of details of an embodiment of a first aspect
invention is shown in FIG 4 showing an inlet drum 40, 43 in driving connection
with a press belt 40, 41. The press belt has an internal surface 40b, 41b and
an external surface 40a, 41b facing the product 9. One or more pressure bars
5 P1, P2, which are configured to slidingly abut the internal surface 40b,
41b to
thereby pre¨compress the product 9 upstream the pressure zone. More than
one pressure bar may be utilized in order to successively pre¨compress the
product in a stepwise manner.
Although FIGS 4, 5A¨D, 7 and 10 only show upper halves of
10 respective press arrangements, i.a. one set of inlet and outlet drums
with
adjoining press belt and press table 51, for the purpose of explaining aspects
of the disclosure, it is apparent to the person skilled in the art that the
corresponding arrangements as illustrated in FIGS 4, 5A¨D and 7 may
preferably be applied also on an opposite side of the product path, as shown
15 e.g. in FIG.1 and 6. It should however be appreciated that the aspects
herein
may be advantageous when implemented in a single belt continuous press or
a double belt continuous press.
As illustrated in FIG. 5A¨D, a product may be fed in the feeding
direction FD by means of the press belt, whereby it is subjected to pressure
in
the pressure zone 70 facilitated by the pressure cushion 51. Due to heat
transfer from the press belt to the product, the binder becomes liquid and
may thereby be referred to as active. An area of the pressure cushion
underneath which the binder is active be referred to as active area. Once the
binder is active, intermolecular cross¨linking occurs at a relatively high
rate,
whereby the binder cures. In order to obtain a stable curing process, it may
be desirable to obtain a curing rate of preferably 95% while the product is
still
in the active area. It follows that a sufficient amount of heat must be
transferred to the product in order to render the binder active in order to
achieve a high curing rate while the product is under pressure. However,
excess heat may raise the steam pressure of the moisture contained in the
product to the extent that it may have undesirable effects on the product
and/or the manufacturing process. For example, if the steam pressure is too
high when the product leaves the pressure zone and the pressure is thus
decreased, the steam may cause blisters in the surface of the resulting
building panel. Also, excessive heat may heat up a core of the product to
such extent that the core may prevent the front layer and back layer from
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cooling off, as heat is then conducted from the inside of the product to the
outside. This phenomenon may cause issues for instance in the further
processing of the building panel, such as in subsequent manufacturing steps
comprising forming of locking systems along the edges of the building panel.
As mentioned, one or more of the drums may heat the press belt, e.g.
by heat transfer where the press belt contacts the drums. This may be
facilitated for example by means of one or more of the drums containing hot
oil.
The continuous press arrangement may compress the product or
reduce the thickness of the product by up to 20%, such as up to 15% or up to
10%.
In a preferred embodiment, the one or more pressure bars and the
one or more pressure cushion may aggregated compress the product or
reduce the thickness of the product by up to 20%, such as up to 15% or up to
10%.
In particular, the one or more pressure bars and the one or more
pressure cushion may successively reduce the thickness to an aggregated
reduction in thickness of the product by at least 10%, preferably at least
15%,
more preferably at least 20%.
In a preferred embodiment, the one or more pressure bars and the
one or more pressure cushion may be configured to obtain an aggregated
compression of the product or reduction in the thickness of the product by up
to 1 mm, preferably 1.5 mm more preferably at least 2 mm.
In particular, the one or more pressure bars and the one or more
pressure cushion may successively reduce the thickness to obtain an
aggregated reduction in thickness of the product by at least 1 mm, preferably
up to 1.5 mm, more preferably at least 2 mm.
In any aspects of the disclosure or combinations thereof, one or more
of the pressure bars may comprise at least one circular cross¨section, for
example the pressure bar may be provided in the shape of a cylinder, such as
a rotatable cylinder. An exemplary embodiment comprising a pressure bar
having at least one circular cross¨section is shown for instance in FIG.4,
FIG.10 and FIGS.5A-5D.
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In any aspects of the disclosure or combinations thereof, one or more
of the pressure bars P1, P-1 may comprise at least one rectangular cross¨
section, for example the pressure bar may be provided in the shape of a
rectangular non¨rotatable bar.
In any aspects of the disclosure or combinations thereof, one or more
of the pressure bars P1, P-1 may comprise at least one rectangular cross¨
section, at least one circular cross¨section, or combinations thereof. For
example one or more pressure bar may be provided in the shape of a
rectangular non¨rotatable bar and one or more pressure bar in the shape of a
cylinder, such as a rotatable cylinder or pressure roller. An exemplary
embodiment of a pressure bar P1 in shape of a rotatable cylinder is shown in
FIG.12.
The feeding velocity of the product 9 through the press arrangement
80 may typically be about 8-10 meters per minute.
The temperature of one or more of the inlet drums 42, 43 may be
configured to heat the press belt and may typically be about 190-210 degrees
Celsius. Thereby, the press belt 40, 41 may have a temperature of about 190
to 210 deg. C as the press belt roll off the drum, such as the inlet drum. As
mentioned, heat may correspondingly be transferred to the press belt 40, 41
via contact with the outlet drums 44, 45.
The press belt may have a temperature Ti as it roll off the inlet drum
42 and an exit temperature T2 as it rolls onto the outlet drum 44. Ti may be
in
the range of 190-210 deg. C and T2 may be in the range of 180 deg. C.
The pressure cushion 55 may be configured with one or more
temperature zones such as a first Za, second Zb third Zc and fourth Zd
temperature zone, as illustrated in FIG.8 and FIGS 10 to 12. Other
configurations are conceivable such as one, two, three, four, five or six
temperature zones. The temperature zones may be configured to facilitate
individual heating of the respective temperature zones, for example active
heating or active cooling along the pressure cushion in the feeding direction.
The temperature in a respective temperature zone may be controlled e.g. by
controlling the temperature of a circulating air flow, for example by means of
a turbo fan.
As will become apparent herein, aspects of the disclosure may
facilitate that the rate of change of pressure increase and/or pressure
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decrease is reduced. Thereby a more even pressure curve is obtained over
the continuous press arrangement 80.
As mentioned, it may generally be desirable to utilize the length of the
pressure zone 70, in the feeding direction FD, to obtain a stable curing
process and thus a stable final product, such as a building panel. A stable
curing process may have been considered obtained when a certain degree of
curing, such as 95% is reached by the time the product exits the pressure
zone. The rate of heat transfer from the pressure belt 40, 41 to the product 9
may increase once the binder of the sub¨layer 11 becomes liquid, therefore,
it may be desirable to reach the point in the process where the binder
becomes liquid early on in the pressure zone 70 since the distance or area of
the pressure zone in the feeding direction FD which is being occupied for
heating the product 9 to the point where the binder becomes liquid
(approximately 90 deg. C) mat thus not be "actively" used. This may be
negative for the economy of space in the press and thus for the economy of
production and thus the economy of the building panel. Accordingly, it may
be desirable to utilize as great area as possible of the pressure zone 70,
remembering that the pressure zone 70 extends over an area of the press belt
40, 41, for the curing process. During the curing of the product, i.a. the
binder, it may be desirable to have the product under pressure, i.a. in the
pressure zone. The product 9 may also typically cool off somewhat as it
propagates through the pressure zone. For reasons already mentioned, it may
be desirable to achieve that the product has cooled off sufficiently by the
time
it exits the pressure zone in order for the steam pressure to be low enough
not to cause blisters. This may be further reason to reach the point where the
binder becomes active at an early point along the product path. As will be
explained herein, aspects of the present disclosure may facilitate that the
pressure applied to the product may be gradually decreased, such as
stepwise decreased, simultaneously as the product cools off between the
pressure zone 70 and the outlet drums 44, 45. Thereby, the conditions
resulting in the formation of blisters may at least to some extent prevented.
The steam pressure exerted by the moisture content of the product,
such as moisture contained in a powder or a veneer, increases with
temperature. Thus, the more energy is transferred to the product, the higher
steam pressure.
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The press belt 40, 41 may preferably have a temperature sufficient to
cause activation of the binder within a certain distance in the feeding
direction or after a certain time period of contact with the product, or a
combination thereof. Once the binder is in liquid state, curing process is
drastically accelerated and the rate of the curing process is increased. It
should be mentioned that a certain degree of curing of the binder may occur
also in non¨liquid state, however this relatively slow curing process may be
neglectable in relation to the rate of curing herein referred to as curing or
in
active state. The rate of the cross¨linking i.e. curing, may depend on
temperature, thus, a certain temperature of the product during curing may be
optimal in order to obtain a stable curing of the product. It follows that a
greater transfer of energy from the press belt to the product may advance the
start of the curing process upstream in the feeding direction, i.e. may
activate
the binder at an earlier position. Should, however the temperature of the
binder be too high, the rate of the cross¨linking reaction may become too
high and the binder may not cure in a stable manner. This may result in
inferior quality of the finished product.
In any aspect, the binder may be provided in powder form.
As discussed, it may be preferable also to consider that the
temperature of the core 10 of the product 9, which may comprise a board,
may preferably not reach too high temperatures at the outlet drums 44, 45.
This is because if the temperature of the core 10 is too high, energy will be
conducted from the core 10 to the surface layer 12 once the surface starts to
cool down. This may compromise further processing such as profiling,
lacquer etc. and may necessitate intermediate storage of the panels prior
further processing.
Cooling and/or heating of the product 9 may be controlled in several
ways, some of which have been discussed above. The temperature zones
may each be cooled or heated. In one embodiment, heat is added via the
inlet¨drums 42, 43 and preferably also the outlet¨drums 44, 45. The press
belt 40, 41 may be passively cooled between the inlet¨drums and the outlet¨
drums. Heat may transfer from the belt 40, 41 to the product 9, thus the belt
may be passively cooled for instance this manner. By means of passive
cooling of the press belt 40, 41, the product 9 may obtain a sufficiently low
temperature as it exits through the outlet drums in order not to compromise
tolerances of locking systems formed along one or more edges of the
finished product, such as a building panel, carried out subsequent a
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continuous press process described herein in a production line for
manufacturing building panels.
As discussed, the product 9 may typically have a varying thickness
prior it enters the pressure zone. The thickness may vary in the feeding
5 .. direction FD and in a direction transverse the feeding direction, such as
in the
width¨direction of the product.
As a result, the product 9 may cause the press belt 40, 41 and the
pressure cushion 55, 55' to tilt or become inclined in the feeding direction
FD
and/or in a direction transverse the feeding direction FD, hence the pressure
10 cushion 55 may pitch and/or roll.
Tilting or pitch and/or roll of the press belt 40, 41 may cause the
pressure zone 70 to leak, whereby the pressure zone 70 is unable to maintain
a desired working pressure PO in the pressure zone 70, such as at least 25
bars, preferably 30-40 bar. Thus, the working pressure PO may be applied to
15 the respective press belts 40, 41 and thereby urge the respective press
belts
40, 41 towards the product path 6 where the product 9 may be arranged, to
thereby press the product 9.
As illustrated for example in FIG.5A¨D, the press arrangement 80 may
20 comprise one or more pressure devices which may be provided in the shape
of pressure bars P1, P2, P3, P4, P4.
The one or more pressure bar may be a fixed non¨rotating member
and/or rotatable members The pressure bar may have a length extending in a
longitudinal direction thereof, corresponding to a direction transverse the
feeding direction and parallel the product path, such as a horizontal
direction.
The pressure bar may have a height extending in a vertical direction and a
width extending in the feeding direction. According to embodiments the
length of the pressure bar is greater than the width, and the width may be
greater than the height. The one or more pressure bars may comprise grooves
distributed along the length thereof for reducing friction against the press
belt.
The pressure bar may be configured to slide against the press belt
while applying pressure to the press belt 40, 41 or roll against the press
belt
while applying pressure to the press belt 40, 41 The pressure bars may be
configured to apply a pressure towards the continuous press belt, in
particular
an inwards¨facing side of the press belt, whereby the press belt is urged,
such as constantly or continuously urged, toward the product path. In FIGS
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5A¨C the pressure is applied in a vertically downwards direction, however it
follows that in the case of one or more corresponding pressure bars arranged
also on the opposite side of the product 9, these pressure bars will urge the
lower press belt upwards towards the product path.
As derivable from FIGS 5A¨B, the pressure bar P1, P-1 may be
arranged on a side of the press belt which is opposite the side of the press
belt facing towards the product path 6 and/or the product 9. The pressure bar
may be configured to push the press belt towards the product. The pressure
bar may be configured to push the press belt towards the product 9 by
applying a pressure of magnitude not greater than the working pressure PO
applied by the pressure arrangement 50 i.e. in the pressure zone 70, such as
50-80%. For example, the pressure bar may apply a pressure of about 25 bar
when PO is about 30 bar.
The pressure bar P1, P-1 may be configured to push the press belt
.. 40, 41 towards the product 9 by applying a pressure of magnitude not
greater
than the clamping pressure PC applied by the pressure cushion 55.
The pressure arrangement 50 may comprise the press table 51 and
the pressure cushion 55.
As derivable from FIG.10, the at least one pressure bar P1, P2 may be
provided in the press table 51 at a position upstream the pressure cushion 55.
In particular, the at least one pressure bar P1, P2 may be provided in the
press table 51 at a position upstream the pressure cushion 55 in the feeding
direction FD, preferably upstream the entire pressure cushion 55.
As derivable from FIG.10, further pressure bars P-1, P-2 may be
provided in the press table 51 at respective positions downstream the
pressure cushion 55. In particular, further pressure bars P-1, P-2 may be
provided in the press table 51 at respective positions downstream the
pressure cushion 55 in the feeding direction FD, preferably downstream the
entire pressure cushion 55.
It follows that the pressure bars may preferably be provided outside
the pressure zone 70 provided within the seal frame 56 and/or the friction
seal
element 57 of the pressure cushion 55.
The one or more pressure bar may be configured to pre¨compress the
product. In particular, the pressure bar may be configured to pre¨compress
the powder layer of the product. Thereby, air is expelled from the powder
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layer, such as about 50% of the air initially contained in the powder layer
may
be expelled. Thus, the pressure bar may facilitate that air is expelled from
one
or more layers of the product. In particular, controlling deairing of the
product
may comprise arranging more than one pressure bar upstream the pressure
cushion 55 in the feeding direction, whereby the product 9 may be
progressively be deaired in a controlled stepwise manner. Further, controlling
deairing of the product 9 may comprise adjusting a pressure applied to the
pressure bar and/or adjusting a pressure applied by the pressure bar to the
press belt.
Control pressure bar with fluid, such as air or oil, or by means of
mechanical pressure, such as a mechanical device.
Thereby, the mean thickness of the product 9 may be reduced.
Thereby, variations in the thickness of the product may be evened out, such
as variations in the thickness in the feeding direction and/or variations in
.. thickness in a direction transverse the feeding direction. Thereby, it may
be
facilitated that the pitching and/or rolling of the pressure cushion 55 may be
is reduced, whereby a desired working pressure PO, such as greater than 25
bar may be facilitated. It is further facilitated that the longevity of seals
58
between the pressure cushion 55 and the press table 51, which may be in the
form of gaskets, is prolonged, since the vertical distance the press belt and
the pressure cushion will be displaced when receiving a product may thus be
reduced.
For example, the pressure bar may pre¨compress the product from
about 15.2 mm to about 12.5 mm, and the pressure arrangement
subsequently compress the product from about 12.5 mm to about 11.7 mm.
Curtesy of the one or more pressure bar, the press belt may be
pushed to abutment with the product. Thereby, heat is more efficiently
transferred from the press belt to the product. Thereby, the product 9 may be
pre¨heated upstream the pressure zone. Thereby, the binder may be
.. activated, i.e. become liquid faster, i.e. earlier, i.e. at a position
upstream in
the feeding direction. This may facilitate more time available for the product
to
cure under pressure in the pressure zone, whereby an improved quality of the
final product may be facilitated.
A surface layer 12 in shape of a veneer layer may to some degree
.. isolate the binder from heat. Therefore, when applying a veneer layer to
the
product such that the binder is comprised in the sub¨layer 11 interspaced
between the core 10 and the veneer, it may have the effect that more heat is
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required cause the binder to become liquid. It may thus be advantageous to
pre¨heat the product 9.
A lower surface of one or more of the pressure bars P1, P-1, in the
vertical direction V, may be configured to extend in a plane vertically below
a
lowermost surface of the inlet drum 42, preferably when the product 9 is fed
through the press arrangement 80.
As explained in relation to the exemplary embodiments of FIGS 4A¨C,
the press arrangement 50 may be provided with various configurations of
pressure bars. As mentioned, one or more pressure bars provided upstream
the pressure zone 70,which may be provided by means of a pressure cushion
55, may facilitate that the pressure applied to the product 9 is gradually
increased in the feeding direction. Thus, in a preferred embodiment one or
more pressure bars are provided upstream the pressure cushion 55 as
derivable e.g. from FIG.10. For example, referring to FIG.5C, a first pressure
bar P1' may apply a pressure of 20 bar, a subsequent pressure bar P2 a
pressure of 25 bar and a further subsequent third pressure bar P3 a pressure
of 30 bar. The number of pressure bars in the press arrangement upstream
the pressure zone, preferably upstream the pressure cushion, may thus be
adapted to obtain a desired rate of increase in applied pressure along the
feeding direction or to avoid sudden increase in pressure applied to the
product, during manufacture of laminate. It generally holds that, in a
sequence of pressure bars arranged upstream the pressure zone, a
subsequent pressure bar may be configured to apply a pressure at least equal
to, preferably greater than a pressure applied by the pressure bar preceding
the subsequent pressure bar.
The corresponding principle may be applied downstream the pressure
zone, as illustrated in FIG.5C, with the object of facilitating a more even
decrease in pressure or pressure relief downstream of the pressure zone,
preferably downstream the pressure cushion 55. Also, as shown in FIG.5D the
feature of providing one or more pressure bars upstream the pressure zone
70, preferably upstream the pressure cushion 55, may be combined with the
feature of providing one or more pressure bars downstream the pressure
zone. It generally holds that, in a sequence of pressure bars arranged
downstream the pressure zone, a subsequent pressure bar may be configured
to apply a pressure equal to, preferably not greater than a pressure applied
by
the pressure bar preceding the subsequent pressure bar. The number of
pressure bars in the press arrangement downstream the pressure zone,
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preferably downstream the pressure cushion, may thus be adapted to obtain a
desired rate of decrease in applied pressure along the feeding direction or to
avoid sudden decrease in pressure applied to the product, during
manufacture of laminate. This may facilitate that the product cools off
gradually in the feeding direction while being under pressure by means of one
or more pressure bars. Thus, the pressure applied to the product by means of
the pressure bars may gradually decrease as the steam pressure of the
moisture of the product also decreases during cooling of the product. For
example, as shown in FIG.5D, the pressure PO may be 35 bar, whereby the
third pressure bar P-1 applies 30 bar and the fourth pressure bar P-2 applies
25 bar. A subsequent fifth pressure bar (not shown) may apply a pressure of
bar. This arrangement may mitigate or at least reduce the occurrence of
blisters in the product which may be caused by a too sudden decrease in
applied pressure to the product, whereby steam may burst out of a layer of
15 the product and cause blisters.
The above principle for the pressure applied by the pressure bars may
be expressed as P1<P2<P3< ===. <Pm <P0 and/or P¨m === >P-3>P-2>P-1,
where positive numbers denotes a pressure applied upstream the pressure
zone 70, preferably upstream the pressure cushion 55, and negative numbers
20 denote a pressure applied downstream the pressure zone 70, preferably
upstream the pressure cushion 55, in the feeding direction. Thereby, a
pressure curve may be obtained over the press arrangement 80.
For example, one or more pressure bars may apply one or more of 15,
20, 25, 30, 35 bar pressure upstream the pressure zone, preferably upstream
the pressure cushion, and one or more pressure bars may apply one or more
of 35, 30, 25, 20, 15 bar pressure downstream the pressure zone, preferably
downstream the pressure cushion in the feeding direction FD.
The pressure bar may comprise temperature resistant material, such
as a composite, for example a composite comprising carbon, such as
graphite composite.
Pressure bar with grooves/recesses, not continuous contact with the
press belt in a direction transverse the feeding direction.
The press arrangement 80 according to embodiments of the first
aspect may comprise one or more controlled temperature zones Za, Zb, Zc,
Zd in the feeding direction as shown in FIGS 7, 8 and 9 in relation to the
third
aspect. The temperature zones may comprise segments of the press
arrangement which can be individually heated or cooled, e.g. by means of
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circulating air. In particular it may be the press belt that is heated or
cooled in
the respective temperature zones. The circulating air in each temperature
zone may be heated or cooled to facilitate stable curing of the product or
reduction of the steam pressure of the product.
5 According to all aspects, the press belt 40, 41 may also be passively
cooled by allowing it cool down by itself. For example, the pressure belt may
collect heat from the inlet drum and then passively cool off along the product
path. The pressure belt may be passively cooled off e.g. by heat transfer to
the product and/or heat radiation to the ambient. Thereby, the energy
10 transferred to the product may be controlled, for example limited such
that a
desired steam pressure of the product and/or temperature of the core of the
product is obtained at the outlet drums. Thus, in this context, passive
cooling
of the press belt may entail that at least a portion of the press belt is not
heated as it propagates along the feeding direction in contact with the
15 product, for example one or more temperature zones may be configured not
to transfer heat to the pressure belt.
FIG.6 shows an exemplary embodiment of a second aspect of the
disclosure. The second aspect may advantageously be combined with
embodiments of the other aspects disclosed herein, such as the first and/or
20 third aspect. The distance between the inlet drums 42, 43, such as the
smallest distance or the distance between their respective longitudinal centre
axis Ax1, Ax2, may be adapted to reduce the distance between the press belt
40, 41 and the product 9 upstream the press table 51, optionally upstream the
one or more pressure bars P1, P2, which may be provided upstream the press
25 table 51. In a preferred embodiment the distance is adapted such that an
angle phi between the product 9 and the press belt 40, 41 is greater than zero
and less than 10 degrees.
The angle phi may be in the range of 0.3 to 1.5 degrees, preferably
0.4 to 1 degree, more preferably 0.5 to 0.8 degrees, most preferred about 0.5
degrees. In this respect, the use of a wood veneer may be advantageous
since, as mentioned, the wood veneer may isolate the sub¨layer and thus
protect it from the heat of the press belt 40, 41 downstream the centre axis
of
the inlet drums Ax1, Ax2. In traditional laminate production, as has explained
herein, the surface layer is typically substantially thinner than a wood
veneer
and may for example typically comprise paper or like. Thus, such thin surface
layers may be substantially damaged by heat from the press belt if the angle
phi is too small, whereby the press belt is in close proximity of the product.
In
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addition, because such traditional thin surface layer, such as 0.2 mm, may
not isolate the sub¨layer, pre¨heating by reducing the angle phi as explained
herein, may not be desired since it may melt and/or destroy the binder.
Preferably, the binder may be heated to a point where it melts or
become active only under the influence of pressure, thus in the pressure zone
70, The distance may be adapted such that the position of the first position
of
contact 3 between the pressure belt and the product occurs earlier and/or is
moved upstream in the feeding direction FD, for example when the product
moves in the feeding direction. By moving the first position of contact 3
upstream in the feeding direction, it may be facilitated that heat is more
efficiently transferred to the product at an earlier instance i.e. upstream.
Also,
due to the reduced angle phi, thermal radiation may heat the product more
efficiently. This configuration may additionally bring about the advantage the
product is pre¨heated, whereby the binder may become liquid faster.
Thereby, the active area of the pressure zone, i.e. the area in which
the binder is in liquid state and the curing process may forego is increased.
Because the active area of the pressure zone is increased, it may be
facilitated that the pressure zone may be reduced in size, thereby improved
economy of the manufacturing process is achieved.
As mentioned, a surface layer in shape of a veneer layer may to some
degree isolate the binder from heat. Therefore, when applying a veneer layer
to the product such that the binder is comprised in a layer interspaced
between the core and the veneer, it may have the effect that more heat is
required cause the binder to become liquid. It may thus be advantageous to
pre¨heat the product.
By adjusting a first position of contact 3 between the press belt and
the product and/or by adjusting the vertical position of the one or more of
the
inlet drums 42, 43 towards the product path a surface layer 12 of the product
9, which may comprise a veneer, may be positioned and/or held in place.
Thereby distortion of the shape of the veneer due to exposure to heat may be
mitigated or at least to some extent reduced. It is further achieved that heat
may be conducted directly from the press belt to the product via conduction.
It follows that thereby the heat transferred from the press belt to the
product
may be increased. Thus, also less heat may be lost due to heat radiation is
dissipated to the ambient.
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Due to the angle phi being reduced, a larger portion of heat radiation
from the press belt may serve to heat the product, thereby product is pre¨
heated. Due to the angle phi being reduced a greater portion of the press belt
may be brought into closer proximity to the product and thus pre¨heating is
facilitated. Consequently, thereby the distance in the feeding direction
downstream the inlet drum required in order for the binder to reach liquid
state may be reduced. Thus, the point along the feeding direction where the
thermal conductivity is increased due to liquification/phase change of the
binder will occur earlier, thereby the "active" portion of the pressure zone
available for obtaining a stable curing is increased. In other words, thereby
the remining distance or area i.e. "active area" available to obtain a stable
curing may be increased, thereby improved quality of the product.
By adjusting the angle phi and/or adjusting the point of first contact
between the press belt and the product, the pressure zone required to obtain
a stable curing of the binder may be reduced, thereby the continuous press
arrangement may be less costly to manufacture, thereby the process and the
building panel may become more economic.
Accordingly, pre¨heating of the product may be adapted by adapting
the distance between the press belt 40, 41 and the product 9 by adjusting the
angle phi.
Accordingly, the angles phi may be adapted to facilitate that a first
position of contact 3 between the respective press belts and a product 9
arranged in the product path 6 occurs upstream the press table 51 and
downstream a respective centre axis Ax1, Ax2 of the inlet drums.
FIGS 7, 8 and 9A¨C show exemplary embodiments of a third aspect of
the disclosure. The third aspect may advantageously be combined with
embodiments of the other aspects disclosed herein, such as the first and/or
second aspect. In the third aspect there is provided a seal system 53.
In any embodiment of the seal system shown in FIGS 9A-9C, FIG.14,
FIG.15, the pressure chamber 59 there may be applied a fluid pressure Pc to
the pressure chamber 59. The pressure Pc may be provided as pneumatic or
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hydraulic pressure. In the embodiment of FIGS 16A-16B the pressure Pc is
provided at least partially by means of a mechanical pressure device.
FIGS 9A-9C shows exemplary embodiments of a seal system 53
according to the disclosure. The seal member 58 may seal against an external
side of the pressure cushion 55 or pressure zone 70 having a first pressure
Pa, such as atmospheric pressure, and on an opposite side, such as an
inside of the pressure cushion 55 against a second pressure PO, such as the
pressure in the pressure zone 70. The pressure gradient between Pc and PO
may be significantly greater then pressure gradient between Pc and Pa, such
as 20 times greater. The ratio PO/Pa may be at least 20.
Accordingly, an outer edge portion of the seal member 58, such as in
a horizontal direction away from the center of the pressure cushion 55, which
seals between Pc and Pa may be subjected to more strain an opposite inner
portion sealing between pressure PC and PA due to the displacement of the
pressure cushion 55 in combination with the greater pressure gradient. The
strain may cause increased wear on the said outer portion of the seal member
58, and may affect the longevity of the seal member 58 negatively.
As discussed, the pressure zone 70 may comprise a pressurizable
volume. The pressurizable volume may be formed on a horizontally inner side
of the displacement groove 60, i.e. towards a center of the press table 51.
The displacement groove 60 may extend continuously in the press table 51 to
form an essentially rectangular groove in the horizontal plane H. The
displacement groove 60 may comprise rounded corners in the horizontal
plane H, as shown in FIG.8.
It is emphasized that the seal systems may be configured to facilitate
a pressure zone 70, in the shape of a pressurizable space or volume,
between the pressure cushion 55, the press table 51 and the press belt 40.
The pressure zone 70 may be pressurized, such as filled up, with fluid, such
as compressed air or oil.
FIG. 14 shows an exemplary embodiment of a further seal system
according to the disclosure. Referring to FIG.14 the seal member 57 has been
omitted. The seal frame 57 is configured seal against the displacement
groove. In particular, the seal frame provides a seal between the pressure
chamber 59 and pressure Pa, such as ambient pressure. Ambient pressure
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may be atmospheric pressure. In particular, the seal frame 56 provides a seal
between the pressure chamber 59 and pressure PO in the pressure zone. This
may be achieved by configuring the seal frame to have sufficiently small
tolerances and/or a tight fit in the displacement groove 60.
FIG. 15 shows an exemplary embodiment of a still further seal system
according to the disclosure. Referring to FIG.15, the friction seal element is
configured to seal against the displacement groove. In particular, the
friction
seal element provide a seal between the pressure chamber 59 and pressure
Pa, such as ambient pressure. Ambient pressure may be atmospheric
pressure. In particular, the friction seal element provides a seal between the
pressure chamber 59 and pressure PO in the pressure zone. This may be
achieved by configuring the friction seal element 57 to have sufficiently
small
tolerances and/or a tight fit in the displacement groove 60.
FIGS 16A-16B shows an exemplary embodiment of a still further seal
system according to the disclosure. Referring to FIG.16A-16B, the friction
seal element 57 is, like in the embodiment of FIG.15, configured to seal
against the displacement groove. In particular, the friction seal element
provide a seal between the pressure chamber 59 and pressure Pa, such as
ambient pressure. In particular, the friction seal element provides a seal
between the pressure chamber 59 and pressure PO in the pressure zone. This
may be achieved by configuring the friction seal element 57 to have
sufficiently small tolerances and/or a tight fit in the displacement groove
60. A
mechanical pressure device 71 is configured to displace in the displacement
groove 60 to thereby apply pressure, such as Pc, to the seal frame 56 such
that the seal frame 56 displace in the displacement groove 60. The seal frame
56 is connected to the friction seal element 57 which displaces therewith in
response to pressure applied to the seal frame 56. A cushion 73, such as a
rubber cushion, may be arranged interspaced between the seal frame 56 and
the friction seal element 57.
One or more of the seal systems of FIGS 14-15,16A-16B may
advantageously be combined along the extension of the displacement groove
60, as explained above.
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The seal arrangement 53 may be configured to facilitate the pressure
zone 70 in a continuous press arrangement. In particular, the seal
arrangement may comprise a seal frame 60 configured to be received in a
press table 50 of the pressure arrangement 50.
5 In particular, the seal system may form part of the pressure cushion 55
and comprise a seal frame 56 configured to be received in a press table 51 of
the pressure arrangement 50. In particular, the seal system may in some
embodiments comprise the seal frame 56 of embodiments of the pressure
cushion 55, the seal frame 56 configured to be received in a press table 51 of
10 the pressure arrangement 50.
The seal frame 56 may be configured to linearly translate inside a
displacement groove 60 of the press table 51.
The seal frame 56 may be configured to linearly translate at least
partially inside a displacement groove 60 of the press table 51.
15 The displacement groove 60 may comprise an innermost wall 61 with
adjacent opposing side walls 62, 63.
The seal frame 56 may comprise a steel frame. The seal frame 56 may
have an inner end portion adjacent an innermost wall of the displacement
groove 60 and an outer end portion adjacent an opening of the displacement
20 groove.
As schematically illustrated in FIG.9A-9B, FIG.14, FIG.15 and FIGS
16A-16B, the pressure zone 70 may comprise a sealed volume by means of
the friction seal element 57providing a seal at least between the pressure
zone and the ambient pressure Pa by being configured to slidingly seal
25 against the press belt. In some embodiments the seal member 58 provides
a
seal between the pressure chamber 59 and a seal frame 56, thereby
effectively closing off a pressurizable portion of the displacement groove 60
from the pressure zone. In some embodiments, the friction seal member 57 in
addition provides a seal between the pressure chamber 59, the pressure zone
30 70 and the ambient pressure Pa, thereby effectively closing off a
pressurizable portion of the displacement groove 60 from the pressure zone
70 and the ambient pressure Pa.
In some embodiments the seal member 58 or friction seal element 57
may seal off an inner wall, such as an innermost wall 61 of the displacement
groove 60, against an adjacent inner end portion of the seal frame 56 to form
a closed pressure chamber or space. Thus, the pressure chamber 59 may be
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sealed off from the pressure zone 70. The pressure chamber 59 may be
configured to be pressurized, e.g. by means of pneumatic pressure or
hydraulic pressure. By providing a pressure chamber 59 configured to be
pressurized, it may be facilitated that the seal member 58 and seal frame 56
and/or the friction seal element 57may be displaced under the action of
pressure extorted by the pressure in the pressure chamber 59. It is thereby
facilitated that the friction seal 57, which is preferably arranged in close
proximity of the press belt 40, 41, may be brought into abutment with and
apply a clamping pressure corresponding to Pc to the press belt 40, where Pc
is dependent on the pressure provided to the pressure chamber 59.
The clamping pressure Pc may preferably be greater than the working
pressure PO provided in the pressure zone 70. For example, the clamping
pressure Pc may be approximately 40 bar and the working pressure PO
approximately 35 Bar.
The friction seal element 57 may comprise a composite, such as a low
friction composite, e.g. a graphite composite capable of withstanding
temperatures of at least 250 deg. C.
The seal member 58 may comprise a gasket, such as a rubber gasket.
The seal member 58 may comprise a substantially U¨shaped cross-
section which is upwards open towards the inner wall 61 of the displacement
groove.
The seal member 58 may comprise a substantially U¨shaped cross¨
section which is upwards open towards the pressure chamber 59. Thereby, a
pressure, such as a fluid pressure, inside the U¨shaped seal member 58 may
cause the U¨shaped seal member to be urged towards the side walls 62, 63
of the displacement groove 60. Thereby, an improved sealing function may be
facilitated.
The U¨shaped seal member 58, as derivable from FIGS 9A-9C
comprises two parallel walls configured to extend parallel respective side
walls 62, 63 of the displacement groove 60. Thereby, a pressure, such as a
fluid pressure in the pressure chamber 59 and inside the U¨shaped seal
member 58 may cause the U¨shaped seal member to be urged towards the
side walls 62, 63 of the displacement groove 60. Thereby, an improved
sealing function may be facilitated.
In particular, side wall 58a of the seal member 58 may be urged
towards the side wall 63 or the displacement groove 60 and side wall 58b of
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the seal member 58 may be urged towards side wall 62 of the displacement
groove 60.
The seal member 58 may be at least partially sandwiched between a
bar 58c, such as a steel bar, and the seal frame 56. The bar 58c may be
arranged inside the U¨shaped seal member 58 and be attached to the seal
frame 56, for example by fastening means extending through the seal member
58. Fastening means may comprise bolts, screws or like. Thereby, a secured
position and orientation of the seal member in the displacement groove may
be facilitated.
The seal member 58 may comprise a non¨symmetric shape. Due to
the non¨symmetric shape it may be advantageous to secure the orientation of
the seal member in the displacement groove.
The displacement groove 60, the seal frame 56, the seal member 58
and the friction seal element 57 may extend continuously along the periphery
of the pressure cushion 55 as shown in FIG.8. The friction seal element 57
may constitute a lowermost, optionally also an outermost portion of the
pressure cushion.
The displacement groove 60 may be tapered, such as to become
narrower in a, for example in a stepwise manner, in a direction from the
opening of the groove towards the inner wall 61. A portion of the
displacement groove 60 adjacent the inner surface may comprise a smaller
cross sectional area, in a horizontal plane H, and a portion of the
displacement groove adjacent the opening may have a larger cross sectional
area. The seal frame may comprise a shape corresponding to the shape of
the displacement groove.
An outer end of the seal frame may comprise means for attaching the
friction seal element, such as a fixing groove configured to receive the seal
member, for example slidingly receive.
The seal member may be fixed to the seal frame and may thus
translate, preferably linearly translate, with the seal frame 56. The seal
member is preferably configured to abut the press belt.
An outer end of the friction seal element 57 may be arranged outside
the displacement groove, an inner end of the seal member may be arranged
inside the displacement groove. The entire seal frame may be arranged inside
the displacement groove.
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The seal frame may be configured to displace in the displacement
groove under the action of a fluid pressure in the pressure chamber 59, such
as pneumatic pressure. The seal member may be caused to translate in a
direction towards the press belt in response to a fluid pressure applied to
the
pressure chamber 59.
The pressure arrangement 50 is configured to apply a clamping
pressure Pc to the press belt via the friction seal element 57. The clamping
pressure Pc may correspond to the pressure provided to the pressure
chamber 59.
According to the disclosure, the pressure cushion 55 may comprise
combinations of any of the embodiments of the seal systems shown FIG.8,
FIG.9A-9B, FIG.14, FIG.15 and FIGS 16A-16B, Thus, according to
embodiments, one or more sections of the pressure cushion 55 may
comprises different seal systems, such as for sealing between Pc and Pa and
PO respectively.
For example, as shown in FIG.8 and FIG. 16A, a corner section 78 of
the pressure cushion 55, such as a corner section 78 where a vertical
displacement of the pressure cushion 55 is greatest, such as closest to the
inlet drums 42, 43, may comprise a seal system being different from a further
section 79, such as a section of a long edge of the pressure cushion 55.
In other words, in a non¨limiting example the cross¨section B¨B (See
FIG.8) taken on a long side of the pressure cushion 55 may comprise an
embodiment of the seal system shown in FIG.9A-9B, FIG.14, FIG.15 and
FIGS 16A-16B and the cross¨section C¨C (see FIG.8, FIG.16A) taken in a
corner section 78 of the pressure cushion 55 may comprise an embodiment
of the seal system shown in FIG.9A-9B, FIG.14, FIG.15 and FIGS 16A-16B,
which may be different from the seal system of cross section B¨B.
Referring to FIG.10 there is shown an embodiment of a fourth aspect
of the disclosure, comprising a continuous press arrangement 80"
combining any embodiments of one or more of the first aspect, the second
aspect and the third aspect. As derivable from FIG.10, the at least one
pressure bar P1, P2 may be provided in the press table 51 at a position
upstream the pressure cushion 55. In particular, the at least one pressure bar
P1, P2 may be provided in the press table 51 at a position upstream the
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pressure cushion 55 in the feeding direction FD, preferably upstream the
entire pressure cushion 55.
As derivable from FIG.10, further pressure bars P-1, P-2 may be
provided in the press table 51 at respective positions downstream the
pressure cushion 55. In particular, further pressure bars P-1, P-2 may be
provided in the press table 51 at respective positions downstream the
pressure cushion 55 in the feeding direction FD, preferably downstream the
entire pressure cushion 55
It follows that the pressure bars may preferably be provided outside
the pressure zone 70 provided within the seal frame 56 of the pressure
cushion 55.
Referring to FIG.11 there is shown an embodiment of a fifth aspect of
the disclosure, comprising a continuous press arrangement 100 wherein any
embodiments of the first aspect and optionally any embodiments of the
second aspect may be combined in a separate continuous pre¨press 81
followed by, in the feeding direction, a further continuous press 82 which may
comprise any embodiments of the third aspect.
ITEMS
ITEM 1. A continuous
press arrangement 80 for manufacture of
building panels, such as floor or wall panels, comprising:
an upper rotatable inlet drum 42 connecting to an upper rotatable
outlet drum 44 via an upper continuous press belt 40 and a lower rotatable
inlet drum 43 connecting to a lower rotatable outlet drum 45 via a lower
continuous press belt 41; said upper and lower press belts configured to form
a product path 6 there between for feeding a product 9 in a feeding direction
FD in response to rotation of said drums or displacement of said press belt(-
5);
an upper and a lower press table Si, Si', each comprising at least
one displaceable pressure cushion 55 configured to be displaced into sealing
abutment with the press belt 40, 41 for facilitating a pressure zone 70
preferably in shape of a pressurizable volume extending along at least a
portion of said path 6.
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ITEM 2. Arrangement according to item 1, wherein the
arrangement 80 comprises one or more pressure bars P1, P2, P3, P-1, P-2,
P-3 disposed upstream and/or downstream the pressure cushion 55, in the
feeding direction FD, wherein said one or more pressure bars are configured
5 to apply a pressure to the upper press belt and/or the lower press belt
respectively in a direction towards the product path.
ITEM 3. Arrangement according to item 2, wherein said
pressure bar(¨s) are provided in the press table 51, 51' and/or between the
10 press table 51 and the inlet drum 42 and/or between the press table 51
and
the outlet drum 44.
ITEM 4. Arrangement according to any one of the preceding
items 2 or 3, wherein said pressure bar(¨s) extends in a horizontal H plane
15 and in a direction transverse the feeding direction FD, preferably at
least
along the entire the pressure cushion, more preferably at least along a
friction
seal member 57 of the pressure cushion 55.
ITEM 5. Arrangement according to any one of the preceding
20 items 2 to 4, wherein one or more of said pressure bar(¨s) are
configured to
pre¨compress the product 9 when being fed in the product path 6, at a
position upstream said pressure zone 70, preferably upstream said pressure
cushion 55, and downstream a respective centre axis Ax1, Ax2 of said inlet
drums in the feeding direction.
ITEM 6. Arrangement according to any one of the preceding
items 2 to 5 wherein the one or more pressure bars constitute non¨rotating
members attached to the press table and configured to slide against the
press belt in response to rotation of said drums 42, 43, 44, 45.
ITEM 7. Arrangement according to any one of the preceding
items 2 to 6, wherein the one or more pressure bars constitute rotatable
members attached to the press table and configured to roll against the press
belt in response to rotation of said drums 42, 43, 44, 45.
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ITEM 8. Arrangement according to any one of the preceding
items 2 to 7, wherein the one or more of the pressure bars are arranged in
successive sequence in the feeding direction.
ITEM 9. Arrangement according to any one of the preceding
items 2 to 8, wherein a subsequent pressure bar P2 of a sequence of
pressure bars arranged upstream the pressure cushion P1, P2, P3, in a
feeding direction, is configured to apply a pressure at least equal to,
preferably exceeding the pressure exerted by a preceding pressure bar P1 in
said sequence.
ITEM 10. Arrangement according to any one of the preceding
items 2 to 9, wherein a subsequent pressure bar (P-2) in a sequence of
pressure bars P-1, P-2, P-3 arranged downstream said pressure cushion is
configured to apply a pressure no greater than, preferably a pressure of less
magnitude than the pressure exerted by a preceding pressure (P-1) bar in
said sequence.
ITEM 11. Arrangement according to any one of the preceding
items 2 to 10, wherein a fluid pressure acting on said pressure bars is
individually controlled for one or more of the pressure bars.
ITEM 12. Arrangement according to any one of the preceding
items 1 to 11, wherein the product 9 comprises a core 9, a sub¨layer 11
.. provided on the core 9, and a surface layer 12 provided on the sub¨layer.
ITEM 13. Arrangement according to item 12, wherein said one or
more pressure bars are configured to control deairing of said product 9, such
as a sub¨layer (11) comprising powder or granulate.
ITEM 14. Arrangement according to any one of the preceding
items 2 to 13, wherein said one or more pressure bars are configured to apply
a compressing pressure corresponding to 50-80% of a working pressure (P0)
applied by the pressure zone 70, preferably 60 to 80%, more preferably 70-
80%.
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ITEM 15.
Arrangement according to any one of the preceding
items 2 to 14, wherein said one or more pressure bars are configured to
facilitate pre¨heating of the product upstream the pressure cushion (55) by
means of urging the press belt towards the product.
ITEM 16.
Arrangement according to any one of the preceding
items 1 to 15, wherein said pressure zone (70) is a pressurizable volume
formed between the pressure cushion (55) and the press belt (40), said
pressurizable space configured to be pressurized by means of pneumatic
pressure.
ITEM 17.
Arrangement according to any one of the preceding
items 1 to 16, wherein said pressure cushion (55) is configured to be
displaced vertically into sealing abutment with the press belt (40) for
facilitating said pressure zone (70), whereby the pressure zone (70)
comprises a sealed volume.
ITEM 18.
Arrangement according to any one of the preceding
items 2 to 17, wherein one or more of the pressure bars comprises at least
one circular cross¨section, such as provided in the shape of a cylinder, such
as a rotatable cylinder.
ITEM 19.
Arrangement according to any one of the preceding
items 2 to 18, wherein one or more pressure bars are movably attached to the
press table, preferably in a vertical direction.
ITEM 20. Arrangement
according to any one of the preceding
items 2 to 19, wherein said one or more pressure bars comprises a material
resistant preferably to at least 250 deg. C temperature, such as a composite,
such as a composite comprising carbon, such as graphite.
ITEM 21.
Arrangement according to any one of the preceding
items 2 to 20, wherein one or more of said pressure bars are configured to
apply pressure to the press belt by means of fluid pressure acting on said
pressure bars, such as pneumatic pressure, such as air, or hydraulic
pressure, such as hydraulic fluid or oil.
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ITEM 22. Arrangement according to the preceding item 21,
wherein said fluid pressure acting on said pressure bars is individually
controlled for one or more of the pressure bars.
ITEM 23. Arrangement according to any one of the preceding
items 2 to 22, wherein said one or more pressure bars are configured to apply
a compressing pressure corresponding to 50-95% of a pressure Pc applied
by the pressure cushion to the press belt, preferably 60 to 90%, more
preferably 75-85%.
ITEM 24. The arrangement according to any one of the
preceding items 1 to 23, wherein said product path has a height measured
from the lower press belt to the upper press belt and a width extending in a
horizontal direction transverse the feeding direction.
ITEM 25. The arrangement according to any one of the
preceding items 1 to 24, wherein each press belt extends continuously about
the respective press table 51, 51'.
ITEM 26. Arrangement according to any one of the preceding
items 12 to 25, wherein said one or more pressure bars are configured to
continuously expel air from one or more sub¨layer 11 of a product 9 while
being fed through the product path 6.
ITEM 27. Arrangement according to any one of the preceding
items 12 to 26, wherein said pressure cushion 55 is configured to reduce the
thickness of the sub¨layer 11 and/or a surface layer 12 of the product 9
and/or the height of said product path 6.
ITEM 28. Arrangement according to any one of the preceding
items 2 to 27, wherein one or more of the pressure bars are received in
respective grooves in the press table.
ITEM 29. Arrangement according to any one of the preceding
items 2 to 28, wherein one or more of the pressure bars are arranged
between press table 51 and said inlet drum 42.
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ITEM 30. Arrangement according to any one of the preceding
items 2 to 29, wherein one or more pressure bars are arranged between press
table 51 and said outlet drum 44.
ITEM 31. Arrangement according to any one of the preceding
items 1 to 30, wherein said press table 51, 51' comprises a displacement
groove 60 and said pressure cushion 55 is configured to be at least partially
received in said displacement groove 60.
ITEM 32. Arrangement according to any one of the preceding
items 1 to 31, wherein said pressure cushion 55 comprises a friction seal
element 57 configured to be in contact with the press belt.
ITEM 33. The continuous press arrangement 80 according to
any one of the preceding items 1 to 32, wherein said pressure cushion 55 is
configured to displace in a vertical direction V towards the press belt in
response to a pressure applied to said displacement groove 60.
ITEM 34. The continuous press arrangement 80 according to
any one of the preceding items 1 to 33, wherein said pressure cushion 55 is
configured to displace in a vertical direction V towards the press belt in
response to a pressure applied to a pressure cushion 55, preferably via said
displacement groove 60.
ITEM 35. Arrangement according to any one of the preceding
items 32 to 34, wherein said seal member 58 and/or seal frame 56 and/or
friction seal element 57 sealingly separates a pressure chamber 59 and the
pressure zone 70, wherein said pressure applied to said pressure cushion 55
is applied via the pressure chamber 59.
ITEM 36. The arrangement according to the preceding item 35,
wherein said seal member 58 and/or seal frame and/or friction seal element
57 is configured to form said pressure chamber 59 with an inner wall 61, 62,
63 of the displacement groove 60.
ITEM 37. The continuous press arrangement 80 according to
any one of the preceding items 1 to 36, wherein said pressure cushion 55
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comprises a seal frame 56 configured to be received in said displacement
groove 60.
ITEM 38. The continuous press arrangement 80 according to
any one of the preceding items 1 to 37, wherein said seal frame 56 is
5 configured to displace in a vertical direction V in said displacement
groove 60
in response to a pressure applied to said displacement groove 60.
ITEM 39. The continuous press arrangement 80 according to
any one of the preceding items 3 to 38, wherein the seal frame 56 is
configured to be connected to the friction seal element 57.
10 ITEM 40. The continuous press arrangement 80 according to
any one of the preceding items 32 to 39, wherein the seal frame 56 is
configured to seal against the pressure applied to said displacement groove
60, such as against a fluid creating the pressure.
ITEM 41. The continuous press arrangement 80 according to
15 any one of the preceding items 32 to 30, wherein the seal frame 56 is
configured to be connected to a seal member 58, wherein the seal member
58 is configured to seal against the pressure applied to said displacement
groove 60, such as against a fluid creating the pressure.
ITEM 42. The continuous press arrangement 80 according to
20 any one of the preceding items 34 to 41, wherein the pressure applied to
said
displacement groove 60 or pressure chamber 59 is provided in the form of
pneumatic pressure, such as pressurized fluid, such as pressurized air.
ITEM 43. The continuous press arrangement 80 according to
any one of the preceding items 34 to 42, wherein the pressure applied to said
25 displacement groove 60 or pressure chamber 59 is provided by in the form
of
hydraulic pressure, such as a hydraulic fluid, such as water, oil.
ITEM 44. The continuous press arrangement 80 according to
any one of the preceding items 34 to 43, wherein the friction seal element 57
is configured to seal against the pressure applied to said displacement
30 groove 60, such as against a fluid creating the pressure.
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ITEM 45. The continuous press arrangement 80 according to
any one of the preceding items 34 to 44, wherein the pressure applied to the
pressure cushion 55 is provided by means of a mechanical device 71, such
as a hydraulic spring, displaceable in said displacement groove.
ITEM 46. The continuous press arrangement 80 according to
any one of the preceding items 1 to 45, wherein the product 9 is a laminate
product comprising one or more sub¨layers 11 and one or more surface
layer(¨s) 12.
ITEM 47. The continuous press arrangement 80 according to
any one of the preceding items 1 to 46, wherein one or more of the surface
layer(¨s) 12 comprises veneer.
ITEM 48. The continuous press arrangement 80 according to
any one of the preceding items 1 to 47, wherein one or more of the sub¨
layers 11 are interposed between a surface layer 12 and a core 10 of the
product 9, wherein the sub¨layer 11 is provided in the form of powder.
ITEM 49. The arrangement according to any one of the
preceding items 37 to 48, wherein said seal member 58 is attached to said
seal frame 56 and configured to displace with the seal frame while sealing
against inner walls 62, 63 of the displacement groove 60.
ITEM 50. The arrangement according to any one of the
preceding items 32 to 49, wherein said seal member 58 or seal frame 56 or
friction seal element 57 is configured to seal off an inner wall 61, 62, 63,
such
as an innermost wall 61 or a bottom wall of the displacement groove, from the
pressure zone 70.
ITEM 51. The arrangement according to any one of the
preceding items 35 to 50, wherein the pressure chamber 59 is configured to
be pressurized, e.g. by means of being configured to be in fluid connection
with a source of fluid pressure, such as pneumatic pressure, such as an
accumulator and/or compressor.
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ITEM 52. The arrangement according to any one of the
preceding items 37 to 51, wherein said seal frame 56 is configured to
displace to bring the friction seal element 57 into abutment with said
pressure
belt for facilitating sealing of the pressure zone 70 formed between said
press
belt, the pressure cushion 55 and the press table 51.
ITEM 53. The arrangement according to any one of the
preceding items 32 to 52, wherein the friction seal element 57 comprises a
composite, such as composite comprising carbon, for example a graphite
composite.
ITEM 54. The arrangement according to any one of the
preceding items 31 to 53, wherein the displacement groove 60 extends
continuously along and essentially parallel the outer edges of the press table
51.
ITEM 55. The arrangement according to any one of the
preceding items 36 to 54, wherein the seal member 58 comprises a gasket,
such as a rubber gasket, configured to slidingly seal against inner walls of
the
displacement groove.
ITEM 56. The arrangement according to any one of the
preceding items 1 to 55, wherein the inlet drums are configured to form
respective angles phi between the respective press belts 40, 41 and the
product path 6 at a position being downstream the inlet drums and upstream
the pressure cushion 55 or press table 51, in the feeding direction FD.
ITEM 57. Arrangement according to item 56, wherein said angle
phi is greater than zero.
ITEM 58. Arrangement according to any one of the preceding
items 56 or 57, wherein the size of the angles phi is adapted by adapting a
distance between the respective centre axis Ax1, Ax2 of the inlet drums, such
as a vertical V distance.
ITEM 59. Arrangement according to any one of the preceding
items 56 to 58, wherein said angles phi are adapted to facilitate that a first
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position of contact 3 between the respective press belts 40, and a product 9
arranged in the product path 6 occurs upstream the pressure cushion 55,
preferably upstream the press table 51, and downstream a respective centre
axis Ax1, Ax2 of the inlet drums.
ITEM 60. Arrangement according to any one of the preceding
items 56 to 59, wherein the angle phi is in the range of 0.3 to 1.5 degrees,
preferably 0.4 to 1 degree, more preferably 0.5 to 0.8 degrees.
ITEM 61. A method of manufacture of building panels 1, such as
floor or wall panels, by means of a continuous press arrangement 80 having
.. an upper rotatable inlet drum 42 connected to an upper rotatable outlet
drum
44 via an upper continuous press belt 40 and a lower rotatable inlet drum 43
connected with a lower rotatable outlet drum 45 via a lower continuous press
belt 41; said upper and lower press belts configured to form a product path 6
there between for feeding a product in a feeding direction FD in response to
rotation of said drums; an upper and a lower press table 51 each comprising
a displaceable pressure cushion 55 configured to facilitate a pressure zone
70 extending along at least a portion of said path 6.
ITEM 62. The method according to item 61, comprising
1. providing one or more pressure bars P1, P2, P3 at one or more
positions upstream said pressure cushion and downstream inlet drums 42, 43
of said press arrangement 80, in the feeding direction;
2. configuring said pressure bars to successively pre¨compress said
product 9 along the feeding direction to thereby reduce a thickness thereof.
ITEM 63. The method according to item 61 or 62, further
comprising
¨ providing a product comprising a core 10, a sub¨layer 11 and a
surface layer 12 on said sub¨layer 11;
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¨ feeding said product in a feeding direction FD to a product path 6
of said continuous press arrangement.
ITEM 64. The method according to item 63, wherein said sub¨
layer 11 comprises a powder and/or a granulate.
ITEM 65. The method according to item 63, wherein said
surface layer 12 comprises a veneer layer , such as a wood veneer, and/or a
paper layer.
ITEM 66. The method according to any one of items 61 to 65,
further comprising:
¨ providing one or more pressure bars P-1, P-2, P-3 at one or more
positions downstream said pressure cushion 55 in the feeding
direction FD;
¨ configuring said pressure bars P-1, P-2, P-3 arranged
downstream said pressure cushion to apply successively reduced
pressures to said product along the feeding direction.
ITEM 67. The method according to any one of the preceding
items 61 to 66, wherein an angle phi is formed between the press belt 40 and
the product 9 at a position downstream a centre axis Ax1, Ax2 of the inlet
drums 42, 43 in the feeding direction, and upstream the pressure cushion 55,
preferably upstream the press table Si.
ITEM 68. The method according to item 67, further comprising
adapting a position of first contact 3 between the product 9 and the press
belt 40, 41, in the feeding direction, by adapting the angle phi.
ITEM 69. The method according to item 67 or 68, further
comprising adapting pre¨heating of the product 9 by adapting the distance
between the press belt and the product by adjusting the angle phi.
ITEM 70. The method according to any one of the preceding
items 67 to 69, wherein said angles phi are adapted to facilitate that a first
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position of contact 3 between the respective press belts and a product 9
arranged in the product path occurs upstream the pressure cushion and
downstream a respective centre axis Ax1, Ax2 of the inlet drums.
ITEM 71. The method according to item 68 to 70, wherein
5 adapting the angle (phi) comprises adapting a vertical position of the
inlet
drum 42, 43.
ITEM 72. The method according to any one of items 67 to 71,
wherein the angle phi is in the range of 0.3 to 1.5 degrees, preferably 0.4 to
1
degree, more preferably 0.5 to 0.8 degrees.
10 ITEM 73. The method according to any one of the preceding
items 67 to 72, wherein said first layer comprises a powder or granulate.
ITEM 74. The method according to any one of the preceding
items 67 to 73, wherein providing the first layer 11 is followed by providing
a
second layer 12, such as a veneer or paper layer, on to said first layer (11).
15 ITEM 75. The method according to any one of the preceding
items 67 to 74, further comprising providing a backing layer 15 to said
product, said backing layer being provided on a side of the board being
opposite the first layer, preferably said backing layer comprises a sub¨layer
11 and a surface layer 12.
ITEM 76. A continuous press arrangement 80 for manufacture of
building panels, such as floor or wall panels, comprising:
an upper rotatable inlet drum 42 connecting to an upper rotatable
outlet drum 44 via an upper continuous press belt 40 and a lower rotatable
inlet drum 43 connecting to a lower rotatable outlet drum 45 via a lower
continuous press belt 41; said upper and lower press belts configured to form
a product path 6 there between for feeding a product 9 in a feeding direction
FD in response to rotation of said drums; an upper and a lower press table
51, 51", one or more of said press tables comprising a displaceable pressure
cushion 55 configured to facilitate a pressure zone 70 extending along at
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least a portion of said path 6, wherein at least one of said press tables 51,
51" comprises one or more pressure bars P1, P2, P3, P-1, P-2, P-3
disposed upstream the pressure cushion, in the feeding direction, wherein
said one or more pressure bars are configured to apply a pressure to the
upper press belt and/or the lower press belt respectively in a direction
towards the product path, wherein the arrangement comprises a continuous
pre¨press device 81, wherein said pressure bars are provided in the press
table 51" of the pre¨press device 81.
ITEM 77. A continuous pre¨press device 81 for use in in the
arrangement according to item 69, said device comprising:
an upper rotatable inlet drum 42" connecting to an upper rotatable
outlet drum 44" via an upper continuous press belt 40" and a lower rotatable
inlet drum 43" connecting to a lower rotatable outlet drum 45" via a lower
continuous press belt 41"; said upper and lower press belts configured to
form a product path 6 there between for feeding a product 9 in a feeding
direction FD in response to rotation of said drums; an upper and a lower
press table 51"; wherein at least one of said press tables 51" comprises one
or more pressure bars P1, P2, P3 disposed upstream the pressure cushion, in
the feeding direction, wherein said one or more pressure bars are configured
to apply a pressure to the upper press belt 40" and/or the lower press belt
41" respectively in a direction towards the product path.
